Method of and apparatus for screening paper stock



m, 19%. MHJEQ A. J. HAUG METHOD OF AND APPARATUS FOR-SCREENING PAPERSTOCK Fil ed No v. 21. 1919 4 Sheets-She l oeooooococoooqnoopoonouocconoou 0 Hum u um @Wiim:

Wm. M, w mmung/59 A. J: HAUG METHOD OF AND APPARATUS FOR SCREENING PAPERSTOCK Filed Nov. 21, 1919 I 4 Sheets-Sheet 2 A. J. HAUG METHOD OF ANDAPPARATUS FOR SCREENING PAPER sTOCK Filed Nov. 21 1919 4 Sheets-Shet zUm. M, a924 1,511,759

. A. .J. HAUG METHOD OF AND APPARATUS FOR SCREENING PAPER STOCK Patented@ct. let, i324 i it 1:15;. i

ANTON J. Have, or NASHU'A, NEW HAMPsnrnn AssIenoa T nurnovnn PAPERmncnrnnnv COMPANY, or nAsnUA, NEW HAMPSHIRE, A CORPORATION or MAINE.

METHOD OF AND APPARATUS FOR SCREENING PAPER 'IOCK.

Application filed November 21, 1919. Serial No. 339,562

To all whom 2'2, may concern:

Be it known that I, ANTON J. Thus, a citizen of the United States, andresident of Nashua, county of Hillsborough, and

b State of New Hampshire, have invented an Improvement in Methods of andApparatus for Screening Paper Stock, of which the following description,in connection with,

lowing description when taken. in connec- 'tion with the accompanyingillustration of one specific embodiment thereof, while its scope will bemore particularly pointed out in the appended claims.

In the drawings Figure 1 is a central, longitudinal, sectional elevationof the inlet end of a-screen embodying one form of the invention;

Fig. 2 is a similar view showing the opposite or outlet end of thescreen;

Fig. 3 is a transverse, sectional elevation taken on the line 3--3 inFig. 1, looking in the direction of the arrow or toward .the inlet end;

Fig. 3 is a detail in section on the line 3 -3 in Fig. 2; a

Fig 3" is a similar section on the line 33 in Fig. 2;

Fig. 4 is a plan view of the devices contained within the screen drumfor advancing the unsereened stock step by step; and

Fig. 5 is a plan view in section, taken on the line in Fig. 3, showingthe separated feed passages for the stock.

Referring to the drawings and to the embodiment of the invention thereinsub mitted for illustrative purposes, I have shown the same as embodiedin a screening apparatus for paper stock, the principal screening memberof which is in the form of a screen drum. While the latter may be of anydesired shape and may be either rotatable or fixed, herein the same isrotatably mounted and polygonal in shape, the surface of the drum beingformed by a series of flat, rectangular, perforated screen plates 10,herein eight in number, carried by the end plates 11 and 12, thelatterbeing octagonal in. outline and secured to or fashioned integrallywith the hollow journal members 13 and 14: respectively.

The entire drum is enclosed within a fixed casing or chamber having theencircling walls 15 secured to the opposite end frame members 16 and 17respectively, the casing 15 at its bottom communicating with a suitableoutletwpassage 18 (Fig. 3) through which the screened stock, which pass.es through the screen drum from the interior to the exterior thereof,may escape and be conducted to any suitable point. The out- .let for thescreened stock is herein shown as provided with a weir-like plate 19over which the stock flows and the height of which controls the level ofthe stock within. the casing. The plate 19 is held at opposite endsbetween guides 20 and 21 and may be replaced by a plate. of greater orlesser height to vary the stock level in the casing.

The casing and theend plate 16 rest upon any suitable support devices,such as the supporting feet 22, and provide a suitable journaled supportfor the rotary screen drum, the same being herein in the form of aplurality of roller supports 23 at each end, upon which rollers thejournal members 13 and le'turn, rotationbeing imparted to thedrum by anysuitable means such as the driving pulley 24 secured to the journalmember 1 Q In the described embodiment of the invention, the stock to bescreened is delivered to the interior of the screen drum at one endthereof, preferably through a continue ous supply; and as the drum isrotated the stock is screened and the unscreened residue lifted anddropped. The unscreened residue, having been first preferably thinned ordiluted, is conducted by suitable feeding means which again deliver itto the drum but at an advanced point in its length so that substantiallythe same screening, lifting and dropping operation may be repeated. Thisis continued any desired number of times until the final unscreenedresidue is delivered to the tailings outlet of the machine.

Referring first to the devices for deliver ing the entering stock to theinterior of the drum and for advancing the enclosed residue step by stepthrough the drum, while prevented from. further advance and divertedagainst the'overfiow plate-49 (Figs.

tions. This repository for the stock is;

such devices may be variously constructed and maybe either movable orstationary, herein they .are contained in a fixed, trough-like structurewhich passes through the drum from end to end and is provided withsuitably arranged passages to direct the flow of the stock in the properdirecsupported on a frame extending through the machine from end to endand consisting of the channel irons and 31 with the underlyingconnecting plate '32, the frame being supported at the inlet end by thebracket 33 secured to the adjacent supporting feet122': andy at' theoutlet end, to brackets 84 which extendoutwardly and rearwardly fromlthesupporting feet 22 and end plate whereit communicates .with the inletchamher 42': and the inlet opening 43, the latter being formed in thecasting 4A which is secured to] the projecting endofthe casting-40.Theinlet passage tl llas a channelshaped depression 45 and the-inletchamber :42 acorresponding depression, which depressiensforma..sand1trapor settling chamher adapted to receive depositsof" sand or other foreignmatter which vmay settle or gravitateout: of: the stock-as the latterenters theinlet chamber and affords passage to thescreen drum; The endof the settling chamber isclosed bya movable closure 46 40,

from time totimeas required;

Thestock as itgfpasses through the inlet through which the chamber maybe cleaned chamber 41 flows over the 'horizontal wall 47 of the castinguntil it encounters the diagonal partitionwallAS by which it is 3 and:5), thelatter being of lesser height than the partition wall 48 andarranged longitudinally thedrum at one side of the axis thereof andpreferably on the descending-side. thereof;' The stock 'passing'over theoverflow plate-49passesdown the surface of. the. inclined" dischargeplate 50 and is thereby delivered to the descending side of the drum,being preferably delivered.

thereto within certain longitudinal limits which-are prescribed by theupright partitionplates-cl' and 52vonIth-e discharge plate,

the-,.-plate 5.2 coinciding with or forming a continuation of thepartition plate 48';

TlieStock whichis thus delivered to the drum, after being. screened andliftedfas will be more fully described) is dropped from the ascendingside of. the drum at the opposite side of'the axis thereof where itagain falls upon the flat plate 47 which at the ascending side of thedrum is preferably inclined upwardly at. 53 (Fig.3) so as to' parts ofthe drum at one sideof the axis thereof (the descending side)" and isinclined downwardly toward the feed plate so that materialwhich iscarried up toward,

to or pastthe center of the drum will drop on the deflectingplate andwill gravitate uponthe flat plate 47. This material, however, gravitatesupon the plate 47 at the back of or on the opposite side of thepartitionwall 48, from' which the stock enters the drum, so that it isseparated from the unscr-eened stock entering-through the inlet and iscaused toflow through the diagonal passage formed between the partitionwall 48 and a similar but more advanced partition wall (31- to a secondoverflow plate 62 on the descending side of the drum but at a moreadvanced point therein than the stock which is initially delivered.thereto from the inlet passage.

The stock which is thus deliveredto the drum past the overflow plate 62for a second screening action is in turn screened, lifted and deliveredto the feed plate 47011 the opposite side of the drum but between thepartition wall 61 and a similar, more 1 advanced partition wall 64, thetwoformagain delivered to the drum at a still more advanced point. Thisoperation may be repeated any desired number of times, the feedingapparatus illustrated in Figs. 4 and 5 being provided with means forrescreening the residue from the firstscreening operation five times,consecutive partition walls 66, 67 and 68 being provided and overflowplates 69 and 70, similar to those already described. Since the repeatedrescreening results in a gradual withdrawal of portions of thestoek anda step-by-step diminution in the amount rescreened at each time,preferably the successive passages in the feeding apparatus undergo a.gradual diminution in. available cross-sectional area, this beingrepresented in Figs. 4 and'5 by a closer arrangement of the successive.partitions for successive feeding passages Between each screening actionand the next, the unscreened residue in each case is preferably thinnedor diluted since the rejections from each screening operation areconsiderably thicker than the initial supply. Suitable thinning ordiluting devices are therefore employedin the illustrated embodiment ofthe invention, the same herein consisting of a shower pipe located insuch position (and herein centrally above the axis of the drum andsup-ported by the feeding plate casting) that it is adapted to dischargea shower of water into and over the gravitating residue. and dilute orthin the same as it flows or moves toward the overflow plates 62 etc.This shower pipe extendstliroughfrom the outletyend of the machine whereit is supported by a bracket 71 carried by the supporting brackets 34:and has connection (not shown) to any suitable source of water supply.

Additional shower pipes may be employed if desired and herein twosuchrpipes 72 and 73 are shown located one directly above the drumwithin the casing 15 and the other above the ascending side of the drum,so that the shower water is directed upon the stock-lifting surface ofthe drum and assists to free the slivers and fibres contained in theunscreened residue from the foraminous surface of the screen plates asWell as assisting in diluting the stock.

After the last screening operation and after the unscreened residue ortailings have been delivered to the feed plate 47 between the partitionwalls 67 and 68, the residue passes over the edge of the plate whereatit is delivered to the inclined plate 81 (see Figs. 2 and 5) and flowsthrough the tailings outlet channel formed by the channel irons 30 and31 and the underlying plate 32, being delivered from the end thereofinto any suitable receptacle such asthe tailings receiver 82.

Referring now to the construction of the screen drum, the latter, in theillustrated embodiment of the invention, is subdivided interiorly intoseparate stock-receiving compartments by means of partition walls "whichextend-longitudinally the drum and are directedinwardly in a generalradial. direction for a short distance. Each screening plate hereincarries three such compartments (Fig. 3) which are formed by the twopartition walls near the edge of the plate and the two intermediatepartition walls 91. These partition walls are brought into successiveregistration with the discharge plate 50 as the drum rotates, so thatthe stock discharged by the discharge plate is delivered to the pocketsand as the drum turns is more or less agitated as it is thrown from onecorner of the compartment to the other. By means of the weir plate 19, asufficient stock level may be ing blades which retain the unscreenedresidue until it is brought within the influence of the shower pipes 73and 72 and is raised to a sufficient elevation to insure its delivcry tothe feedplate 4L7. i

In the described embodiment of the invention, also, the screen drum isfurther subdivided longitudinally into separate screening compartmentsby a series of circumferential, ring-like plates 9292, these.

ring-like plates constituting partition walls which are located tocoincide or register with the partition walls 51, 52, etc. which controlthe successive deliveries of stock to the successive portions of thedrum, and also to register or coincide with the successive partitionwalls :8, 61, etc. on the feed plate and which confine the unscreenedresidue as it is delivered thereto by the drum to such a path as insuresits redelivery to the drum in the next succeeding circumferential.compartment thereof. These circumferential partition walls thereforesubdivide the drum into compartments corresponding to the successivefeed passages of the feeding plate so that at each successiverescreening the unscreened stock is confined to a part of the drum whereit is separated from portions of the stock which have been subjected toa greater or lesser number \of screenings, thus insuring that all stockdelivered to the drum will be subjected to substantially the samescreening eifect before being rejected at the tailings outlet.

As a simple and etlicient means of constructing the screen drum, theperforated plates 10 are carried each by a grid-like support whichextends from one end plate 11 to the opposite end plate 12, the oppositeends of each plate being fastened by the bolts (Fig. l) to the end ring.

Each grid-like support is composed of the longitudinal partition. walls90 and 91 and the segmental, circumferential partition walls 92. Whenthe several supports are bolted in position to the end plates, they forma skeleton support for the perforated plates 10 with the correspondingcircunr ferential partition walls in registration so as to constitutethe circumferential partitions 92.

The partition walls 90 at the edge of each grid-like support areconsiderably thickened at the base or where the plate 1.0

is adapted to rest thereagainst so that when perforated portions of theplates 10 If desired, at suitable points longitudinally in the adjacentpartition walls 90 the adjoining supports may be bolted together bymeans of bolts 101 (see Fig. 2 and the section Fig. 3*). To secure theplates to the d rum, means are herein employed which eifectively holdthem in position and at the sametime assist in drawing the thin platesflat upon the. support. For this purpose, herein the adjacent edges ofadjoining plates are engaged by the beveled or wedgeshaped: strips 102,the face of each strip being engaged at intervals by beveled faceclamps, each clamp consisting of a pair of clamping members 103 whichare drawn together by the'bolt 104, the bolt being anchored or heldagainst a radial outward movement by a strap 105 which is secured to apin 106 arranged transversely'in the underlying and adjoining partitionwalls 90.

As the bolt 104 is tightened, theclamps are i drawn together andthis inturn binds the edges of the plates 10 tightly to the grid-like supportsand tends to stretch them fiat thereon. At opposite ends each plate-issimilarly clamped to the end plates 11 and 12 respectivelyby thewedge-shaped strips 107 clamps 108 and clamping bolts 109 (Fig. 1).

The drum is thus actually made up of segmental units, each unit servingas the-sole P support for the plate corresponding to that segment.Therefore any one plate or any one segment maybe removed and replacedwithout dismantling the drum.

Preferably, at each opposite end of the casing removable closures areprovided such as'the closures 110 and 111 throughwhich an inspection ofthe interior of the apparatus may be had at any time and through whichanytrouble maybe corrected which arises, such for example as acloggingofthe feeding passages or improperlyworking shower pipes. The end plates11 and 12 are provided withsuitable' openings 112 through whichinspection of and access to the interior of the drum can readily be hadthrough the respective inspection openings.

1 The-feeding passages of the feed platebeing opened and exposed, anytendency to clog or obstruct the feed .is reduced to a minimum and, ifor whenit occurs, can be easily ascertained through the inspection.openings referred to.

To provide against an accidental stoppage of the drum rotation, as forexampleby the slipping of the drive belt, an overflow may be providedwhich will take careof stock in the drum likely to accumulate before thefeed of the stock supply can be shut ofi. For this purpose the end.plate 17 hasan overflow opening 113 fromwhich there projects an overflowspout 11 i throu h which stock may escape over the weir p ate 115,

in case the drum, through any such ac cidental stoppage, becomes filledwith stock to a height sufiicient to permit it to escape through theopenings 112 in the endplate 12.

In order to better adapt the tailings to.

some subsequent process of refinement or for some other reason, it maybe desirable to thicken the-consistency of the tailings by. T8. movingsome of the moisture which they have when discharged. For this purpose Ihave shown the screen near its tailings outlet equipped with a dryingdevice adapted to remove water from the taihngs, such drying deviceherein'consisting of the rotary,

cylindrical, fora-minous drying drum 120 which is secured to the end ofthe journal member 14 to turn therewith about the tailings outletpassage. thicken the ta1l1ngs, a cover plate 121, which is normally usedto cover an opening 122 in the bottom of the tailings passage, isremoved so that the tailings are discharged through the opening 122 intothe draining drum 120. The latter is slightly flared. or.

longitudinally tapered so that as the drum;

turns the tailings are slowly advanced to.-

ward' the mouth thereof until discharged;

into the tailings receptacle 82. Inthe course. of their advance throughthe drum, how

ever, they are agitated more or less and;

rolled over and over asthey are carriednp the ascending side of thedrum. This ex,- tracts more I or less water from. the stock, which waterfalls into the underlying chamber 123, escaping through the passages 12%which lead downwardly and inwardly through the end plate 17. intothe-screened stock chamber. The exposed portion of the tailingsdischarge passage and the draining drum 120 may becovered. for.-protection by. the removable, se1nicylindrical cover130.

Thedelivery of the shower pipe 70, as.

well as that of the pipes 72 and 73, isrcone fined to an area within themain casing 1.5, so that there is no further dilution of the tailingsafter they enter the draining drum 120. 1

.VVhile I have herein shown anddescribed for purposes of illustration,one specifiee1nbod'iment. of the invention, it is to be understood thatthe same is not limited to the details of construction herein'shown orto. the form or relative arrangement of parts,

If it is desired to.

but that extensive deviations may be made therefrom without departingfrom the spirit of the invention.

Claims:

1. A screening apparatus for paper stock, the same having a rotaryscreen drum the interior of which is subdivided longitudinally intoseparate screening compartments whereby the stock delivered to the inletend may be screened, lifted and dropped by the rotation of the drum, andstock-advancing means comprising a repository for the dropped stock withseparate passages, one for each screening compartment, adapted toadvance the residue. from each screening operation and deliver it to thenext or more ad vanced compartment of the drum, said passages at theirreceiving end registering with the delivery from one compartment and attheir delivery end with the next adjacent compartment of the drum.

2. A screening apparatus for paper stock, the same having a rotaryscreen drum the interior of which is subdivided longitudinally bycircumferential partition walls into separate screening compartments andis subdivided circumferentially by longitudinally arranged partitionwalls, whereby the stock delivered to the inlet end may be screened,

lifted and dropped by the rotation of the drum, and advancing meanscomprising a repository for the dropped stock with separate passages,one for each screening compartment, and adapted to advance the residuefrom each screening operation and deliver it to the next, more advancedcompartment of the drum, said passages registering at their receivingend with the delivery from one compartment and at their delivery endWith the next adjacent compartment of the drum.

3. A screening apparatus for paper stock, the same having a rotaryscreen drum subdivided both circumferentially and longitudinally intoscreening compartments, said drum, having an inlet at one end wherebystock may be delivered to the drum and an outlet at the opposite endwherebiy the tailings may be withdrawn there rom, and means to receivethe tailings emptied from each screening pocket as the same are liftedin the course of rotation of the drum and deliver the same to ascreening compartment on the next or more advanced series for arepetition of the screening o eration.

4. A screening apparatus or paper stock, the same having a rotary screendrum subdivided both circumferentially and longitudinally into screeningcompartments, said drum having an inlet at one end whereby stock may bedelivered to the drum and an outlet at the opposite end whereby thetailings may be withdrawn therefrom, means to receive the tailingsemptied from each screening pocket as the same are lifted in lengthwisethe drum, a stock repository device extending through the drum andpresenting feeding passages adapted to receive stock from onecompartment and advance it to the next, each of said passages havingpartition walls which coincide at their stockreceiving end with onecompartment and at their delivery end with the circumferental partitionwalls of the next adjacent compartment.

6. A screening apparatus for paper stock, the same having a rotaryscreen drum the interior of which is subdivided by circumferentialplates to present separate screening compartments, each compartmentbeing also subdivided longitudinally by plates, toprovide lifting bladesfor the separate compartments, said drum having an inlet through whichstock tobe screened may be delivered to a compartment near the inlet endand screened, lifted and dropped through the rotation of the drum, andstockadvancing and feeding means whereby the residue from each screeningoperation is advanced and delivered to a more advanced compartment inthe drum for a repetition of the screening operation, the samecomprising a repository member in the form of a plate having dividingwalls presenting open passages adapted to conduct the deposited residuediagonally from the point deposited at one side of the drum axis to amore advanced point on the opposite side, thereceiving end of thepassages registering with the delivery of one compartment of the screenand the discharge registering with the next more advanced compartment.

7. A screening apparatus for paper stock, the same having a rotaryscreen drum by which the stock is screened, lifted and dropped, andstock-advancing or feeding means comprising a trough-like repositoryconsisting of a plate with dividing walls to present uncovered passagesadapted to conduct the deposited residue diagonally from a point on oneside of the drum axis to a more advanced point on the opposite side andthereat deliver it again to the drum.

8. In a screening apparatus for paper stock, the combination with ascreen drum adapted to screen, lift and discharge the unscreened residuethrough the rotation of the drum and means for delivering the unscreenedresidue fro-m any screening operation again to the drum, the same havingdiagonally arranged feeding passages 10- catedi above'the axis of thedrum and terlatter drum.

stock, the combinationwith a screen drum 'minating at'an inclineddischarge plate, the providing a path to the underlying 9.1;In' ascreening apparatus for paper adapted to screen, lift and discharge, theunscre'ened residue through the rotation of the drum and means fordelivering the unscreened residue from any screening operation again tothe-drum, the same having 1 diagonally arranged and open feedingpassages located above the axis of the drum. 10. The combination with arotary screen v drum of means to deliver stock within said drum, the;stock. being screened and the residue lifted and dropped, and meanstodeliverthe residue again to said drum, said means including a feedingplate with diagonally arranged uncovered feeding passages thereon;

11;.An apparatus for screening paper stock: having a rotary screen drumprovided with interior lifting blades; said drum beingj adapted toscreen the stock and lift and drop-the uns'creened residue, and meansfor advancingthennscreened residue with-- infthe drum, the sameincluding a downwardly directed discharge plate adjacent the bottom ofthe drum withthe end of which theliftingbladesare, adapted to registerin succession as the drum rotates.

12. An apparatus for screening paper stock, the-same having arotary'screen drum adapted to screen the stock, lift and drop the same,and means for advancing-the stock-within said drum, the same including asubstantially flat. plate provided with diagonally arranged feeding.passages.

' 1 3; -An; apparatus for screening paper stock, the same having arotary screen drum adapted to screen the stock, liftand drop the same,and means foradvancing the stock -ly arranged feeding withinsai'd.,drum,}the same including a substantially flat plate provided withdiagonalpassages and an overflow wall for each passage.- 7

14. An apparatus for screening paper .downwardly directed dischargeplate for vconductingthe unscreene'd residueto the des'cending sideofthe drum. p g e 1115, A screening apparatus includinga rotary screendrum with circumferential partition compartments and stock-advancingmeans including delivery passages having partition walls confining the,delivery thereth coinciding With the circumfe efit se en-ments 1 6, Arotary. screen drum" having a foram nous surface and subdivided intoscreening compartments by longitudinal partitions, saidzcompartmentsbeing further subdivided circumferentially.

17. In an apparatus for screening paper stock the combination with ascreen drum having a polygonal cross-section, the interior being dividedinto screening com )artments by longitudinal subdivisionsan thecompartments being subdivided into successive series bycircumferentially arranged partitions, of stock advancing devices adapted to receive stock from one compartment and deliver it to a moreadvanced one.

18. In an apparatus for screening paper stock the combination with ascreening drum having a foraminous surface and subdivided interiorlybot-h circumferentially and longitudinally into separate screeningcompartments by unperforated partition walls, of stock advancing devicesadapted to receive stock from one compartment and deliver it to a moreadvanced one.

1.9. Inan apparatus for screening paper stock, the combination with ascreening drum, polygonal in cross-section and presenting successive,flat, foraminous faces,

.each' flat face being interiorly subdivided by longitudinal partitionwalls into separate screening compartments, of stock advancing devicesadapted to receive stock from one compartment and deliver it to a moreadvanced one.

'2 20. In an apparatus for screening paper stock, the combination with ascreening drum having a polygonal cross-section and having one or morelongitudinal partition walls between each vertex of the polygon toseparate each flat face thereof intcriorly into two or more screeningcompartments, of stock advancing devices adapted to receive stock fromone compartment and deliver it to a more advanced one.

21. A screening drum'polygonal in cross section and sepaatcdinteriorlyand longitudinally into separate screening compartments and apartition member located at .or near the junction of two adjacent fiatfaces and havingpartition walls which converge inwardly.

, 22. A screen drum having a polygonal cross-section separatedinteriorly into longitudinal screening compartments and a partitionmember between two adjacent compartments and located atthe juncture oftwo adjacent-faces of the drum, said partition member being thickened atthe point nearest the drum face.

23. A rotary screen drum subdivided interiorly into separate screeningpockets by longitudinal partition members, one of said partition membershaving partition walls which converge inwardly.

24. A polygonal screen drum havin end supports, aforaminous wall for eacflat face of the drum, a grid like support for each foraminous walladapted to be fastened at opposite ends to the end supports and topresent each a plurality of longitudinal walls adapted to constitutestock-lifting blades and a plurality of transverse walls adapted toregister in adjacent supports and when assembled to constitute interiorcircumferential partitions, the adjacent supports presentinglongitudinal walls closely adjacent one another and converging inwardlytoward each other.

25. A screen drum having a polygonal cross-section, end supports and aforaminous wall for each flat face of the drum, a gridlike supportadapted to be fastened at opposite ends of the end supports andpresenting each a plurality of longitudinal walls adapted to constitutestock-lifting blades, the adjacent supports presenting longitudinalwalls closely adjacent each other and converging inwardly and towardseach other.

26. A rotary screen drum having a foraminous surface and composed of aplurality of grid-like members secured at opposite ends to suitable endsupports and serving as a support for the foraminous covering, saidgrid-like members presenting longitudinal partition walls adapted toserveas interior stock-lifting blades for the drum.

27. A rotary screen drum comprising end supports, a foraminous coveringand a support for the foraminous covering, the same including aplurality of separate supports fastened at their opposite ends to theend supports and presenting longitudinal blade members adapted tosubdivide the interior of the screen into separate screeningcompartments.

28. A rotary screen drum comprising end supports, a foraminous coveringand a support for the foraminous covering, the same including aplurality of separate supports fastened at their opposite ends to theend supports and presenting segmental, circumferentially arrangedpartition members.

29. In a screening apparatus, a rotary screen drum having a polygonalcross-section with means for supplying stock to the interior of thedrum, said drum being composed of end supports with a connectinggrid-like supporting member for each flat face of the drum and afora-minous plate secured to said supporting member.

30. A rotary screen drum having a foreminous covering and a supporttherefor com prising end supports and a series of apporting unitsconnecting the same, each unit providing a seat to which opposite edgesof the foraminous covering is applied and also presenting interiorlyarranged, stoclelifting blades.-

31. A rotary screen drum having a forarninous covering and a supporttherefor formed of sectional segments, each segment comprising asupporting member for the foraminous cover and presenting subdividingpartition. walls for the interior of the drum.

32. A screening apparatus for paper stock having a rotary screen drumprovided with means for screening the stock and lifting and dropping theunscreened residue, means for advancing the unscreened residue betweeneach screening operation and the next, a stock inlet through which stockis deliv ered to one end of the drum, said inlet having a settlingchamber to receive sand and other impurities.

33. A screening apparatus for paper stock having a rotary screen drumprovided with means for screening the stock and lifting and dropping theunscreened residue, means for advancing the unscreened residue betweeneach screening operation and the next, a stock inlet through which stockis delivered to one end of the drum, said inlet having a settlingchamber to receive sand and other impurities and having also a cleaningopening for said settling chamber.

34. A screening apparatus for paper stock having a rotary screen drum,stock inlet means and a settling chamber for said stock inlet meansadapted to receive sand and other impurities.

i A screening apparatus for paper stock having a rotary screendrum,stock. inlet means and a settling chamber for said sto l: inlet meansadapted to receive sand and other impurities, said chamber having acleaning opening.

36. A screening apparatus for paper stock, the same having a rotaryscreen drum with means for screening the stock, lifting and.

dropping the unscreened residue, means for advancing the stool; aftereach screening operation, means for diluting the stock between eachscreening operation and the next, a tailings delivery outlet and meansfor thickening the tailings.

37. A screening apparatus for paper stock, the same having a rotaryscreen drum with means for screening the stock, lifting and dropping theunscreened residue, means for advancing the stock after each screeningoperation, means for diluting the stock between each screening operationand the next, a tailings delivery outlet, a tailings drying device andmeans for diverting the tailings at will to said drying device. 7

38. A pulp screen for screening paper stock in comprising a screen drumhaving stock-lifting walls and means for rotating the crum whereby thestock is screened and the unscreened residue lifted and dropped by saidliftingwalls, means fOr diluting the thickened residue, devices toreceive the discharged residue and divert and deliver it to said drum ata more ad vanced point therein for a repetition of the screening action,and a draining drum to receive the tailings, outside of the actionofsaidfdiluting means, whereby the consistency' of said tailingsmay bethickened.

39.. A pulp screen for screening paper 7 stock; in stages comprising ascreen drum having stock-lifting walls and means for rotating the drum"whereby the stock is screened and the unscreened residue lifted anddropped by said lifting walls, means "for diluting the thickenedresidue, devices to receive the discharged residueand divert "anddelivert to said drum at a moread- 'vanced point therein for arepetition of the thickening the 'tailings.

iOJA 'pulp screen for screenlng paper stock in stages comprising ascreen drum screening action, and drying means for having stock-liftingwalls and means for rotating the drum whereby the stock is screened andthennscreened residue lifted and dropped by said lifting walls, meansfor diluting the thickened residue, devices ;to receive the dischargedresidue and divert and deliver it to saididrum at a more ad i .vancedpoint therein for a repetition of the ll. A

; screening action, drying means for thieken ring the tailings and meansfor discharging I the tailings at Wlll \Vlt-ll or wlthout the actionthereon of said drying means.

screening apparatus for paper stQck,'the same'havin'g a rotary screendrum, acasing'therefor, means whereby stock may be screened by said'drumand the residue liftedand dropped, feeding means for advancing theunscreened residue and deliver- 'ingit again to the drum, and one ormore I removable closures in said casing to permit "a casing therefor,means whereby said drum is adapted to screen the stock and lift and dropthe unscreened residue, a stock reposiaccess to vthe interior of thedrum. 412; A screening apparatus for paper stock, the same having arotary screen drum,

tory for taking theunscreened residue and redelivering it to the drum ata morev advanced' point, the same comprising a sta- ,overflow openingstopermit the overflow of tionary feed member having diagonally arrangedfeed" passages therein, and one or moreremovable closures for saidcasing to provide access to said feed member 43. A screening apparatusfor paper stock, the same comprising a rotary screen drum, a 03.811121therefor and means for feeding stock to the nterior of said drum, saidcasingand said drum having cooperating said stock in the said drum.

44;. A screen, drum having a foraminous covering, a support thereforpresenting a seat onwhich the covering rests and means for securing saidforaminous covering to event of the stoppage of the'support, the sameincluding aiclamping device with a clamping face beveled or inclinedwith relation to the seat.

1-5. A screen drum having a polygonal cross-section and a foraminouscover composed of fiat foraminous plates, an underly ing support andi'ueans presenting a seat on which the covering rests for securing theplates to said support, the same including a beveled strip overlying theedge of the plate and one or more clamping devices engagingsaid strip,the clamping faces of said strip and device being incline-d or beveledwith relation to the seat.

46. A screen drum having a polygonal cross-section and a formaminouscovering composed of a plurality of flat foraminous plates, and meansfor securing'theplates to an underlying support including beveled stripsoverlying the edges of adjacent plates and wedge-shaped clamps engagingthe edges 'of the strips and adapted to be clamped together to hold saidplates in position. I

4?. A screen drum, polygonal in crosssection and having a foraminouscovering composed of flat foraminous plates and means for fasteningtheedges of said plates to an underlying seat or support for the samecomprising a clamping device and an intermediate member interposed.between the clamping device and the face of the plate, said membershaving cooperating eugaging faces inclined at an angle to the seat onwhich the plate rests 48. The combination with a screen having atailings outlet ofa drying device comprising a, rotary draining drumadapted: to receive said tailings on its inner surface and drain theWater therefrom, said drum having separate discharge passages for thewater and the thickened'tailings. V 49; The combination with a screenhaving means for screening paper stock and for V diluting andrescreening the unscreened resi- V vate and discharge the stock asthecylinder rotates, a series of compartments into which the stock isdischarged from said dippers, said dippers and compartments coacting toadvance the stock through the cylinder, and sprays directed across thepath of the stock between its discharge from the dippers and return tothe cylinder.

52. In a structure of the class described, the combination of aforaminated cylinder, a series of internal dippers adapted to elevateand discharge the stock as the cylindei rotates, a series ofcompartments into which the stock is discharged from said dippers,

said dippers and compartments coacting to advance the stock through thecyiinder, and 10 means for agitating the stock Within the compartments.

In testimony whereof, I have signed my name to this specification.

ANTON J. HAUG

